Field of the Invention
Example embodiments relate generally to nuclear Boiling Water Reactors (BWRs), and more particularly to a system and a method for a containment vent system. The system may be passive, such that the system may be operated for extended period without the need for monitoring by on-site plant personnel or the application of external electrical power following initial activation of the system. The system may protect the integrity of primary containment during a serious plant accident.
Related Art
During a nuclear power accident, nuclear boiling water reactors (BWRs) predominantly rely on a primary containment structure 1 (see FIG. 1) to prevent radioactive materials (gases, liquids and particulates) from being released into the surrounding environment. However, in modern history, three severe nuclear accidents (Chernobyl, Three Mile Island, and Fukushima) have involved a release of radioactive materials from primary containment structures of a nuclear plant.
Conventionally, a venting system 10 connected to the wetwell 4 (the space between the drywell 8 and the suppression pool 6 of a BWR) of a BWR reactor 2 may also be used to release vapor from the reactor 2 to relieve pressure during a serious plant accident (such as a partial meltdown, or a complete meltdown of the reactor core). The conventional venting system 10 often includes a wetwell vent line 12 with inner and outer containment isolation valves (CIVs) 3a/3b used to vent vapor from the wetwell 4 directly to the atmosphere during periods when over-pressurization of primary containment 1 may cause structural damage that could escalate a release of radioactive material into the environment. However, the conventional venting system 10 may be inadequate in truly assisting plant personnel as the system 10 generally requires continuous on-site monitoring (during a time when multiple high priority demands may exist). For instance, a conventional venting system 10 requires the opening and closing of the inner and outer containment isolation valves (CIVs) 3a/3b (which act to discharge vapor from the wetwell 4) by on-site plant personnel that are necessarily required to react as plant conditions change during a serious plant accident.